Oxidation of aniline over titania pillared montmorillonite clays
Oxidation of aniline over titania pillared montmorillonite clays
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DOI：
10.1016/j.clay.2006.04.001
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发表时间：
2006-07
影响因子：
5.6
通讯作者：
N. Jagtap;V. Ramaswamy
中科院分区：
文献类型：
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作者：
N. Jagtap;V. Ramaswamy
采用常规搅拌(方法I)和超声搅拌(方法II)结合水热处理技术合成了二氧化钛柱撑粘土(Ti-PILC)。表征结果表明，采用超声波法可以明显缩短钛纳米管的形成时间。后续的水热处理提高了样品的结晶度，使锐钛矿型的二氧化钛转变为金红石型的二氧化钛。在搅拌法制备的样品中，金红石相更加突出。对样品的UV-Vis研究表明，由于量子尺寸效应，其吸收带发生蓝移。这表明柱撑粘土中的大部分二氧化钛的尺寸可能远低于10 nm，这一点得到了X射线衍射和平均孔径的支持。柱撑粘土催化剂在H_2O_2氧化苯胺反应中具有很好的应用前景，在本工作条件下可选择性地生成偶氮苯。苯胺的转化率和产物分布在很大程度上取决于催化剂浓度、H_2O_2与苯胺的摩尔比、溶剂的性质和氧化剂。以甲醇为溶剂时，苯胺的转化率和偶氮苯的选择性较高。
Titania pillared clays (Ti-PILC) have been synthesized employing conventional stirring (method I) and ultrasonic agitation (method II) techniques followed by hydrothermal treatment. The characterization results revealed the formation of Ti-PILC with significant reduction of time when ultrasonic method was used. Subsequent hydrothermal treatment on the samples has resulted in the increase in the crystallinity and the transformation of anatase TiO2to rutile TiO2. The rutile phase is more prominent in the samples prepared by stirring method. UV–Vis studies on the samples exhibit blue shift in the absorption band due to the quantum size effect. This indicates that a major part of TiO2in the pillared clay could be well below 10 nm in size, which is supported by XRD and the average pore size. The pillared clay catalysts have proved to be promising in aniline oxidation with H2O2, selectively forming azoxybenzene under the working conditions. The aniline conversion and the product distribution largely depended on the catalyst concentration, H2O2to aniline mole ratio, the nature of the solvent and the oxidant. Higher conversion of aniline and greater selectivity for azoxybenzene was obtained with methanol as the solvent.